I’m learning a lot about home ventilation and attic insulation this year.
Our home is pretty old – fortunately, it’s pretty liveable and in decent condition. No fundamental issues of mold, rot, insects, etc. – but there are quite a few strange conundrums there, one of which is the ventilation – or lack thereof – in our “attics” behind the kneewalls, as well as what I’d call the true attic at the apex of the roof.
There is a ventilation fan on the south side of the house, in the true attic area over Lucia’s room. However, it was not in operation during the home inspection, and it appears not to be working at all at the moment. We can’t even properly tell if it’s hooked up to the home wiring, and if so, where. The closest kneewall area to it is mostly filled by the built-out closet space that someone added in semi-recent history, obscuring the view of the space between the rafters where wiring might otherwise be visible. Usually such units also have a thermostat which causes them to kick on when it gets hot, but there is no control panel visible ANYWHERE in proximity to it. What the fuck.
The southwestern side of the roof (over our bedroom), meanwhile, gets quite hot. Really, the whole upstairs gets very toasty, but especially that room. There is no insulation at all behind the slanted portion of the wall – just airspace between the plaster and lathe and the inside of the roof. As far as we can tell, there is 0 insulation in the true attic space as well – the ceilings are frigid in winter and toasty warm in summer. This is what is currently inspiring me to just cut a goddamn hole in between the rafters over the upstairs landing and go the fuck up there and lay down some batts.
I went poking around in the crawlspace yesterday evening looking at the polystyrene baffles left there by a previous owner. These are normally used to allow airflow between spaces like our kneewalls and attic (when they are actually insulated with batts or other insulation fill, so it provides a rigid channel that keeps the fluff from blocking airflow needed in an operation that includes a fan drawing air out of the attic space), or between soffit vents to the outside and attic spaces. I found that the polystyrene baffles fit right into the spaces in the rafters – yay! - leaving a goodly chunk of space there for insulation, if we can find something rigid that can slide into the space underneath to shield the room within from the hot hot heat (some 1-1.5 inch radiant barrier might work). However, I could not determine if the soffit vents are open at all. Given, I was looking for light from the outside on a cloudy, rainy evening, but I didn’t see a thing. Since our fan is not operating, this might not be a problem as of yet. Also, the kneewall attic space was quite dry – very warm, but quite dry. The usual problem with improper ventilation and insulation, aside from poor temp control, is that humidity condenses in these uncontrolled spaces – either humid attic air condenses on cooler interior walls, or the reverse, and damages the wall material as well as making a happy home for molds and rot to wreck your living space. Our kneewall attics are dry and mold-free, however that may be because the upstairs is often closer to the temp of the attics, and there isn’t a lot of humidity being pumped into the living space OR the attic spaces. Except during the winter, I suppose – and then it isn’t a whole lot, just enough to moisten the air – not akin to the steam after a shower.
I half wonder if the fan isn’t currently working because someone opted to unwire it without de-installing it. Or maybe it stopped working – if there are no open soffit vents, it could have been struggling to vent hot air because there was no intake to complement the exhaust and broken down.
So, the questions remain – should we attempt to rehabilitate/replace the ventilation fan? If we do, will we have to actually open holes in the soffits where there are vented covers under the eaves?
My first instinct is to at least attempt to put the radiant barrier insulation along with the baffles in the slanty walls over our bedroom to at least reduce some of the heat conduction, and maybe fulfill my fantasy of slicing a hole into the true attic and laying down some batts of insulation to keep things cooler now and warmer in the winter. I suspect this would also let me know what’s up in Lu’s room vs ours; hers looks as though it’s been newly drywalled whereas ours is plaster; whoever drywalled MAY have actually insulated her room properly from above when they did so.
As for the fan and soffits, that may need to wait a little; it feels as though some of it is DIYable, but the project as a whole may require professional consultation and perhaps professional labor, something I’m not quite ready to take on at this point in the season/our home investment.